Product removed for interval_color_mapping tutorial

[grallewellyn]

For this tutorial, items_response = requests.get(f"{stac_endpoint}/collections/{collection}/items/{item}").json()
Returns {'code': 'NotFoundError', 'description': 'Collection NASA_JPL_global_agb_mean_2020 does not exist.'} because the product was removed from MAAP

Should also upgrade to use pystac client instead of direct requests